WO2013004715A1

WO2013004715A1 - Device and method for a shear

Info

Publication number: WO2013004715A1
Application number: PCT/EP2012/062962
Authority: WO
Inventors: David Stonecliffe
Original assignee: Siemens Vai Metals Technologies Ltd.
Priority date: 2011-07-07
Filing date: 2012-07-04
Publication date: 2013-01-10
Also published as: GB201111582D0; CN204194919U; GB2492581A

Abstract

A device (1) comprises a shear for shearing an article (2); a sensor (4, 5); an actuator (6, 8); and a control unit (10). The control unit (10) is adapted to determine deviation in alignment of a cut (W) applied to the article and to control activation of the actuator in response to the determined deviation; wherein the actuator comprises a pair of steerable pinch rolls.

Description

DEVICE AND METHOD FOR A SHEAR

This invention relates to a device and method of controlling alignment of material for shearing, in particular when using a side trim shear.

Existing shears for metal plate may use pinch rolls or a travelling clamp arrangement to try to prevent sideways movement of the plate in the shear and to keep to the desired cutting line.

Conventionally, the problem of the plates not shearing correctly, has been addressed by very careful alignment of the pinch rolls, roller tables and shear. Even a small misalignment error can result in curved cuts.

In accordance with a first aspect of the present invention, a device comprises a shear for shearing an article; a sensor; an actuator; and a control unit; and wherein the control unit is adapted to determine deviation in alignment of a cut applied to the article and to control activation of the actuator in response to the determined deviation;

wherein the actuator comprises a pair of steerable pinch rolls. .

The present invention addresses the problem of cuts deviating from the required line, due to misalignment of the article along a transport path through the shear, by sensing position or movement of the article and determining the existence of a deviation and exerting a force to move the material back into alignment, using steerable pinch rolls.

Preferably, the actuators further comprise pushers; magnetic aligners; and head or tail clamps.

Preferably, the device comprises a plurality of sensors.

Preferably, the device comprises a plurality of actuators.

Preferably, the actuators are positioned upstream or downstream of the pair of pinch rolls.

In accordance with a second aspect of the present invention, the device comprises a shear, a set of pinch rolls comprising two pairs of pinch rolls on opposite sides of a transport path of a material to be sheared; a sensor; and a control unit;

wherein the control unit is adapted to control the speed of one of the pairs of pinch rolls on one side of the transport path, relative to the speed of the other one of the pairs of pinch rolls on the opposite sides of the transport path in order to adjust alignment of the material entering the shear. In this embodiment, the problems of misalignment of the article along a transport path through the shear are addressed by altering the relative synchronisation of each of the pairs of pinch rolls to move the material back into alignment

Preferably, the sensors are positioned upstream or downstream of the shear Preferably, the device further comprises at least one pair of additional pinch rolls, the additional pinch rolls comprising steerable pinch rolls.

Preferably, the pair of additional pinch rolls is mounted on the same side as a datum pair of pinch rolls.

Preferably, the sensors comprise at least one of edge detectors, or displacement detectors.

An example of a displacement device is a laser surface displacement device.

Preferably, the edge detectors are positioned downstream of the shear and the displacement detectors are positioned upstream of the shear.

Preferably, a plurality of sensors are provided at intervals upstream and downstream of the shear.

Preferably, the article comprises a metal plate, slab or strip.

In accordance with a third aspect of the present invention, a method of controlling alignment of a material for trimming with a shear device, the device comprising a shear, one or more sensors, one or more actuators and a control unit, comprises passing a material to be sheared through the device along a transport path in a direction of travel; at the controller, receiving signals from at least one sensor indicating movement of the material transverse to the direction of travel; and correcting alignment of the material by applying a correcting force with at least one actuator; wherein the at least one actuator comprises a pair of steerable pinch rolls.

Preferably, the control unit stores a cut profile for the article to be sheared; wherein data received from the sensor is compared with the cut profile; and where deviation from the cut profile is determined, the control unit activates the at least one actuator to apply a correcting force.

Preferably, the correcting force is applied by pairs of steerable pinch rolls Preferably, the correcting force is applied by additional pinch rolls on only one side of the article.

In accordance with a forth aspect of the present invention, a method of controlling alignment of a material to be sheared in a device comprising a shear, a set of pinch rolls comprising two pairs of pinch rolls on opposite sides of a transport path of the material to be sheared, a sensor and a control unit, comprises passing the material through the device along the transport path in the direction of travel; at the controller, receiving signals from the sensor indicating movement of the material transverse to the direction of travel; and correcting alignment of the material by adjusting the speed of one of the pairs of pinch rolls on one side of the transport path, relative to the speed of the other one of the pairs of pinch rolls on the opposite sides of the transport path.

Preferably, the method further comprises, after detecting movement of the material transverse to a direction of travel of the article, determining and applying an adjustment in differential velocity of the set of pinch rolls or of additional pinch rolls on only one side of the article.

Preferably, the signals are received from sensors downstream of the shear.

Preferably, the signals are received from edge detectors.

Preferably, the method further comprises receiving signals from sensors upstream of the shear.

Preferably, the signals are received from displacement detectors.

Preferably, the method further comprises determining and applying a slew to the actuators.

An example of a device and method in accordance with the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates the effect of using conventional side trim shears; and, Figure 2 is an example of a device according to the present invention.

In the field of shearing materials such as metal plates, slabs or strips, whether continuous or pre-cut lengths, there can be problems if the material is not correctly aligned as it passes through the shear. Although the examples described below are given in the context of shearing metals, such as steel or aluminium, the invention may also be applicable to other non-metal materials, such as composites or plastics, where the effect of misalignment of the material passing through the shear would result in curvature at the edges of the sheared material. The invention is particularly applicable for shearing thicker materials, such as plate, where prior art methods relying on bending and putting a thin strip under tension cannot be used. When side trimming metal plates or strips it is very important that the shear follows a straight line. However, in practice, side trimming shears often produce a slight curvature in the cut edge. Fig.l illustrates how a material being sheared may end up with curvature in the cut edge W and / or an angle U between the divide shear cut and the side trim. V is the curvature of the cut across the width produced by the divide shear, which is not addressed by the present invention and U is the angle between the divide shear cut and the side trim cut, caused by misalignment between the divide shear cut and the side trim shear cut. U may be caused by either curvature along the plate W or by 'crabbing' i.e. an overall sideways movement during side-trimming.

In existing side trim shears for metal plate, there is usually at least one set of pinch rolls, typically comprising four pinch rolls in total arranged as an upper and lower pinch roll on each side of the plate, across the width of the plate. Generally one pair of pinch rolls, datum pinch rolls, on a datum side of the shear is fixed axially, whereas the other pair of pinch rolls, moveable pinch rolls, is moveable axially to accommodate different widths of plate. Typically the two lower pinch rolls, on either side across the width, are connected together via e.g. a splined shaft to ensure that both lower pinch rolls turn at the same speed, although on a modern shear they might be electrically synchronized. However, this still requires very careful alignment of the pinch rolls, roller tables and shear and only a small error may result in curved cuts. If the axis of the pinch rolls is not at exactly 90 degrees to the direction of the cut then sideways forces are exerted on the plate. These forces may create a small rotation of the plate in plan view - which results in a curved cut - or they may move the plate sideways in the shear, or both. Similarly, any misalignment of the roller tables may also produce sideways forces on the plate which may result in curved cuts.

The present invention addresses the problem of curved cuts obtained with conventional side trim shears by actively controlling the position of the material being sheared in response to signals from sensors upstream or downstream of the shear. The principle is to determine the deviation in alignment from the required alignment, for example by detecting the edge position and / or the transverse movement of the material or plate as it passes along the roller table and through the side trimming and slitting shears. This may be done by using edge detectors on exit tables, or by using a series of laser surface displacement devices on the entry side, similar to those used for length measurement, but orientated in the transverse direction. Alternatively, a combination of edge detection on the exit side and surface displacement detection on the entry side may be used, with the sensors placed at intervals on both the exit and entry roller tables. Surface displacement transducers are preferred on the entry side because on the entry side the material has not yet been trimmed and the material will have width variations and curvature along its length. Consequently it would not be possible to determine whether the entry side is running straight from edge detection sensors alone. The determined deviation is then used as the basis for applying a suitable correction to the material.

Fig.2 illustrates an example of a device 1 according to the present invention including all of these options, but as mentioned above, it is not essential to have all types and position of sensor together in order for the invention to work. A material to be sheared 2 moves in a direction of travel indicated by arrow 3, along a transport path. For trimming of metal slabs, there is typically a roller table, along the top of which the slabs move. At least one sensor 4, 5 is positioned to detect either the position of a cut edge 11 of the material, or to detect displacement. The sensors may be position sensing transducers or movement detectors, implemented for example, as edge detectors, or laser surface displacement devices. An indication of whether there is any movement of the material out of alignment is sent to a control unit 10 which determines from the received signal whether the deviation out of alignment is sufficient to require remedial action and if so, what action to take in response. The sensors may send regular data to the control unit for interpretation, or may only send a signal indicative of displacement beyond a given threshold. Performance is enhanced by using detectors that are sensitive enough to pick up small movements indicating that an error in alignment is starting to develop, so that corrections can be made before the variation exceeds the allowable value.

Although, in its simplest form, the one or more sensors measure the position of the cut edge 11 at least one position downstream of the shear and then use this measurement to correct the steering of the material coming into the shear by adjusting the synchronisation between the pinch rolls, or by steering the pinch rolls, accordingly, accuracy can be further improved by also using displacement sensors on the material before it enters the shear and adjusting alignment of the material. An advantage of the embodiments of the present invention is that they can be retrofitted to existing plants to improve quality of the rolled product. Having detected movement or deviation from the expected position, then correction can be made using the actuators, which in this example are the pinch rolls 8. For short plates this correction may be done by slight adjustment to the synchronisation of the datum and non datum side pinch rolls at the shears. Preferably the pinch rolls are electrically synchronised (not mechanically), so that it is possible to slightly speed up or slow down one side relative to the other side. Alternatively, the adjustment may be done mechanically, for example, with a differential type mechanism. However if the plate is of a reasonable length then the pinch rolls will not have sufficient grip to change the alignment of the plate. The roller table friction will be too high.

To address this, the system may include additional pinch rolls 6, either on one or both edges of the material, which are steerable at small angles, typically 1 or 2 degrees for errors in alignment of a few mm per metre, but perhaps up to 5 degrees in cases of significant misalignment, to generate a sideways force to move the plate back into a straight line. If only on one side, it is preferred that the additional pinch rolls are positioned on the datum side. By steerable is meant that these pinch rolls can be rotated about a vertical axis, or otherwise moved in such a way as to create an angle which is slightly greater than, or slightly less than, 90 degrees between the axis of the pinch rolls and the direction of movement of the plate in order to create a sideways force. The additional pinch roll pairs may be incorporated along the datum edge of the entry and exit roller tables, spaced at regular intervals, of, for example, about 10 m. These pinch rolls are capable of being pivoted about their vertical axis.

Side trim shears can be of two types - rotary side trim shears which cut continuously and rocking blade type shears where the shear makes a cut of typically 1 to 1.5 m in length and then the plate is moved forward by this distance ready for the next cut. In the latter case the acceleration requirement is quite high because the shears do typically 30 cuts/min and so the pinch rolls have to accelerate the plate and move it forward and stop it within a very short time. The additional pinch rolls can be made lighter if they do not have to accelerate the plate and may be individually powered. One mechanism for slewing these rolls uses a small hydraulic cylinder (linear transducer and proportional valve).

As described above, if the pinch rolls do not have sufficient grip to change the alignment of the material by means of a change in synchronisation alone, then the preferred way to generate a sideways force on the plate to counteract any sideways forces due to misalignment of the pinch rolls 8 or the roller tables is to use the steering pinch rolls 6. In some situations, further actuators, such as magnetic aligners, such as electro -magnets, or for thick plates, mechanical pushers, may be used in combination with the set of pinch rolls. Magnetic aligners are usually used to align the plate before shearing starts - they grip the plate magnetically and then can be moved sideways in order to move the plate sideways or to rotate the plate in plan view by moving the aligner at one end of the plate relative to the aligner at the other end. However, although a magnetic aligner could exert sideways force, it also needs to move along with the plate, which is less easy to engineer. Pushers (i.e. hydraulically or electrically actuated beams which push against the edge of the plate) are only suitable for use on thick plates, as they would buckle the edge of thin plates. Another option is to use a clamp or clamps which grip the head and/or tail of the plate and move along with it, but can also be moved sideways to exert a sideways force.

If there is lateral translation of the plate as well as angular rotation then this may be corrected by pivoting the main pinch rolls 8 in the same direction as the auxiliary pinch rolls. If they all pivot in the same direction then the plate will move bodily sideways as it travels forwards and thereby correct its translational error.

In the example of the device shown, a set of entry and/or exit pinch rolls, comprising at least one pair of pinch rolls 8 on either side of the transport path, is provided, in contact with the material and adapted to exert a force on the material to adjust the alignment of the material in response to a control signal from the control unit. The pinch rolls of the present invention are able to exert a sideways force on the surface of the material to move the material for alignment purposes, in response to a signal from the control unit. The invention may also be implemented by applying slight changes to the synchronization between the pinch rolls on either side of the shear, i.e. by speeding up or slowing down one side relative to the other, in response to data from the one or more sensors 4, 5 received at the control unit 10. The pairs of pinch rolls may be upstream or downstream of the shear, or both. The synchronisation may be achieved by means of mechanical or electrical actuators and control. Although mechanical control is possible, e.g. with a differential gearbox, electrical actuators are simpler to implement.

For the purpose of illustration, Fig.2 shows the use of laser surface movement detectors 4 on the ingoing table and edge detectors 5 on the outgoing side. In this configuration of pinch rolls it is possible to correct for any angular variation in the line of travel of the plate. The principle assumes that there is no lateral translation of the plate at the shears 10. When a variation of the entry and exit side detectors 4, 5 is signalled, then error in the line of travel can be computed and a correction made by differential velocities of the shear pinch rolls 8 and a corresponding slewing of the auxiliary pinch rolls 6.

Another option for implementing the invention is that the entry and exit pinch rolls 8 perform their conventional function and simply act to prevent sideways motion of the material as it passes through the shear, but the steerable pinch rolls 6, are provided upstream or downstream of the shear to steer the material in response to signals from the sensors 4, 5 being sent to the control unit 10, indicating a need to correct the alignment. Alternatively, the pinch rolls 8 are steerable as well, although as these are big heavy pinch rolls and the mechanism to move them would be expensive, this is not the preferred implementation.

The detailed examples given assume that the aim is to maintain a straight cut by correcting alignment of the article to prevent curvature due to sideways movement of the article in the shear. However, in certain circumstances a curved cut is desired and by appropriate modification of the cut profile stored in the control unit, the data received from the sensors may be used to activate the actuators and positively apply movement to the article in a direction, such that the resulting cut follows a particular target curve.

Claims

1. A device, the device comprising a shear for shearing an article; a sensor; an actuator; and a control unit; and wherein the control unit is adapted to determine deviation in alignment of a cut applied to the article and to control activation of the actuator in response to the determined deviation; wherein the actuator comprises a pair of steerable pinch rolls.

2. A device according to claim 1, wherein the actuators further comprise at least one of pushers; magnetic aligners; and head or tail clamps.

3. A device according to claim 1 or claim 2, wherein the device comprises a plurality of sensors.

4. A device according to any preceding claim, wherein the device comprises a plurality of actuators.

5. A device according to claim 4, wherein the actuators are positioned upstream or downstream of the pair of pinch rolls.

6. A device, the device comprising a shear, a set of pinch rolls comprising two pairs of pinch rolls on opposite sides of a transport path of a material to be sheared; a sensor; and a control unit; wherein the control unit is adapted to control the speed of one of the pairs of pinch rolls on one side of the transport path, relative to the speed of the other one of the pairs of pinch rolls on the opposite sides of the transport path in order to adjust alignment of the material entering the shear.

7. A device according to any preceding claim, wherein the sensors are positioned upstream or downstream of the shear

8. A device according to any preceding claim, wherein the device further comprises at least one pair of additional pinch rolls, the additional pinch rolls comprising steerable pinch rolls.

9. A device according to claim 8, wherein the pair of additional pinch rolls is mounted on the same side as a datum pair of pinch rolls.

10. A device according to any preceding claim, wherein the sensors comprise at least one of edge detectors, or displacement detectors.

11. A device according to claim 10, wherein the edge detectors are positioned downstream of the shear and the displacement detectors are positioned upstream of the shear.

12. A device according to any preceding claim, wherein a plurality of sensors are provided at intervals upstream and downstream of the shear.

13. A device according to any preceding claim, wherein the article comprises a metal plate, slab or strip.

14. A method of controlling alignment of a material for trimming with a shear device, the device comprising a shear, one or more sensors, one or more actuators and a control unit; the method comprising passing a material to be sheared through the device along a transport path in a direction of travel; at the controller, receiving signals from at least one sensor indicating movement of the material transverse to the direction of travel; and correcting alignment of the material by applying a correcting force with at least one actuator; wherein the at least one actuator comprises a pair of steerable pinch rolls.

15. A method according to claim 14, wherein the control unit stores a cut profile for the article to be sheared; wherein data received from the sensor is compared with the cut profile; and where deviation from the cut profile is determined, the control unit activates the at least one actuator to apply a correcting force.

16. A method according to claim 15, wherein the correcting force is applied by the pairs of steerable pinch rolls.

17. A method according to any of claims 14 to 16, wherein the correcting force is applied by additional pinch rolls on only one side of the article.

18. A method of controlling alignment of a material to be sheared in a device comprising a shear, a set of pinch rolls comprising two pairs of pinch rolls on opposite sides of a transport path of the material to be sheared, a sensor and a control unit; the method comprising passing the material through the device along the transport path in the direction of travel; at the controller, receiving signals from the sensor indicating movement of the material transverse to the direction of travel; and correcting alignment of the material by adjusting the speed of one of the pairs of pinch rolls on one side of the transport path, relative to the speed of the other one of the pairs of pinch rolls on the opposite sides of the transport path.

19. A method according to claim 18, wherein the method further comprises, after detecting movement of the material transverse to a direction of travel of the article, determining and applying an adjustment in differential velocity of the set of pinch rolls or of additional pinch rolls on only one side of the article.

20. A method according to any of claims 14 to 19, wherein the signals are received from sensors downstream of the shear.

21. A method according to any of claims 14 to 20, wherein the signals are received from edge detectors.

22. A method according to any of claims 14 to 21, wherein the method further comprises receiving signals from sensors upstream of the shear.

23. A method according to any of claims 14 to 22, wherein the signals are received from displacement detectors.

24. A method according to any of claims 14 to 23, wherein the method further comprises determining and applying a slew to the actuators.